- Invasive Species Management
Invasive Species Management
2023 Japanese Beetle Citizen Science Project
Landowners may enter their information to help us better understand the Japanese beetle populations along the Front Range.
We will be using our online map to track early emergence and document the preferred Colorado hosts.
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Need Noxious Weed Advice?
- For properties within unincorporated Jeffco - We are able to answer calls and questions. Our hours are Mon -Thur 6:30 am - 5 pm. See our contact information on the right-hand side of this page.
- For properties within city limits please contact your city's weed authority.
Weed of the Month
Each month we will feature a noxious weed to help landowners identify weeds they may encounter on their property.
Plumeless thistle
June 2023
Plumeless thistle (Carduus acanthoides) is a List B member of the Sunflower family (Asteraceae). It is a biennial or sometimes a short-lived perennial.
Flowers are reddish-purple, ½-1 inch wide. The bracts are narrow and tipped with a spine. Flowers are present June to September and grow singly or in small groups at the tips of branched stems.
Plumeless thistle reproduces by seed. The seeds lack a pappus.
Plants have taproots and can grow to 8 feet tall. Stems are winged and branch towards the ends. Leaves are dark green with a lighter midrib. The undersides of the leaves are hairy.
Rosettes form in the first year and bolt early in May to June of the next year. The rosette leaves are deeply lobed and spiney.
Plumeless thistle is found in disturbed areas, such as overgrazed pastures, rangelands, roadsides, and rights-of-way.
Originally from Eurasia, it has been known in the northeast US since 1837 and in Colorado since the mid-1950s.
WASHINGTON STATE Noxious Weed Control Board
Photo Credits
Rosette - Loke T. Kok, Virginia Polytechnic Institute and State University, Bugwood.org
Stem - Steven Katovich, Bugwood.org
All others: Jeffco Invasive Species Management
A Landowner's Guide - Developing a Noxious Weed Management Plan
We developed this guide to assist landowners. The information provides steps to develop a management plan for properties that have noxious weeds.
Weed Spotter
The Weed Spotter program is a citizen science based effort to detect 6 high priority species on Jeffco Open Space parks. Learn more at our Citizen Science page.
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Invasive Species Management
Physical Address
700 Jefferson County Parkway, Suite 100
Golden, CO 80401
Phone 303-271-5989
Hours
Monday - Thursday
6:30 a.m. - 5:00 p.m.
Notices
Noxious Weed Treatments
Jefferson County Open Space will be applying herbicides for noxious weed control at the following parks.
Week of 5/29
- Deer Creek Park
- Hildebrand Rch Park
- North Table Mtn
- South Table Mtn
- South Valley Park
Week of 5/22
- Apex Park
- Crown Hill Park
- Deer Creek Canyon Park
- Hildebrand Ranch Park
- Matthews/Winters Park
- South Valley Park
- Van Bibber Park
Trailheads at:
- Apex Park
- Hiwan Heritage Park
- Matthews/Winters Park
- Mount Galbraith Park
- North Table Mountain
- Elk Meadow Park
- Meyer Ranch Park
- Pine Valley Ranch Park
- Reynolds Park
Ongoing
During 2023, in addition to our normal noxious weed treatments, we will be performing forest restoration work at these locations. We will be treating parts of the sites with herbicides throughout the season. The maps below show the work areas within the parks.
Alderfer Three Sisters Map (pdf)
Please give our crews and contractors room to work.
Dates and locations subject to change.
Always visit the main kiosk at the individual park for current information.